Jeannie C. Kelly, MD, is Fellow in Maternal-Fetal Medicine, Tufts University School of Medicine/Tufts Medical Center.

Errol R. Norwitz, MD, PhD, is Louis E. Phaneuf Professor and Chairman, Department of Obstetrics and Gynecology, Tufts University School of Medicine/Tufts Medical Center. He serves on the OBG Management Board of Editors.

The authors report no financial relationships relevant to this article.

Nearly 100% of pregnant women infected with Ebola die. Clinicians should be aware of this statistic and familiar with general, as well as pregnancy-specific, protocols.

“[Pregnant patients infected with the Ebola virus in West Africa] aren’t given preferential treatment...They aren’t even given beds.…They are assumed to die. Priority is given to the patients whom the health-care workers believe they can save. In effect, pregnant women are being triaged last.”

—Joshua Lang1

Ebola is a rare and potentially deadly disease caused by infection with a strain of the Ebola virus. First described in 1967,2 the Ebola virus has caused significant morbidity and mortality in many parts of sub-Saharan Africa. Awareness about this disease has increased dramatically in the United States as a result of the largest Ebola epidemic in history, which broke out in West Africa in 2014. The 3 countries most widely affected include Sierra Leone, Liberia, and Guinea. As of May 15, 2015, there were 26,798 cases of Ebola in this epidemic (with 14,971 laboratory confirmed), of whom 11,089 have died.3 There have been a total of 868 confirmed health care worker infections reported in Guinea, Liberia, and Sierra Leone since the start of the outbreak, with 507 reported deaths.4

It is highly unlikely that an Ebola epidemic of similar proportion will break out in any developed nation. However, isolated cases of Ebola have been identified among high-risk individuals in the United States (such as those who had recently served as medical volunteers in West Africa), which has raised concern about Ebola infection prevention and management in this country.

Little is known about Ebola infection in pregnancy. The few reports available suggest that pregnant women who become infected are highly contagious, with a maternal and perinatal mortality rate near 100%.5 Significant efforts were put in place in hospitals around the United States, including in labor and delivery units, to care for potentially or actively infected individuals, to protect health care workers, and to contain the spread of any new infections. It is important that clinicians be aware of the efforts and the recommended protocols—especially for the unique circumstance of infection during pregnancy. We review these protocols, as well as provide details on viral transmission and treatment.

What is Ebola virus and why are humans affected?

Ebola virus is a single-stranded RNA filovirus (FIGURE) with 5 independently identified species named after the countries or regions in which they were identified. Four of these are known to cause disease in humans, including Zaire Ebola virus, Sudan virus, Tai Forest virus (isolated in Ivory Coast), and Bundibugyo virus.1 Zaire Ebola virus is the most virulent species and has been responsible for most of the outbreaks in sub-Saharan Africa, with an overall mortality rate of around 70%.2 Sudan virus was responsible for outbreaks in the 1970s, 2000, and 2004; Bundibugyo virus caused a single outbreak in 2007, which had a lower mortality rate of around 30%. The fifth virus, Reston virus, does not appear to cause infection in humans, but does infect pigs and nonhuman primates.1

The natural reservoir of the Ebola virus is not known. It is unlikely to be primates, since the virus typically kills its primate host within a matter of days. Recent studies suggest that the natural host may be bats.3 Initial infections in humans may result from preparing and eating infected bush meat or from exposure to infected bat droppings during such activities as mining and spelunking.

Transmission and clinical presentationEbola is not spread through air, water supply, food, or by mosquitoes.6 The Ebola virus is spread from person to person through direct contact with blood or bodily fluids from an infected individual who has developed disease symptoms. It is generally accepted that asymptomatic individuals are not infectious, likely due to their low circulating viral load. The incubation period is between 2 and 21 days.6,7

Sexual transmission. The Centers for Disease Control and Prevention (CDC) now recommends that contact with semen from male Ebola survivors be avoided “until more information regarding the duration and infectiousness of viral shedding in body fluids is known.” They recommend a condom be used (correctly and consistently) when male survivors have oral, vaginal, or anal sex.8

Following the initial inoculation, the virus spreads rapidly throughout the body, infecting many cell types, although it primarily targets macrophages (including the Kupffer cells of the liver), dendritic cells, and endothelial cells. Infected cells die and release more viral particles as well as proinflammatory mediators (tumor-necrosis-factor−a, interleukins, nitric oxide) leading to a massive systemic inflammatory response. Impaired dendritic cells are unable to mount an effective immune response to fight the infection.9